摘要

This paper focuses on the analysis of fatigue life for main steam isolation valve (MSIV) in nuclear power plants (NPPs). The contraction of throat is also in the form of sonic resonance cavity, which causes big vibration and noise. The vibration result in the fretting fatigue, which is the reason of the contact surface damage of the disc and the disc guide. By using FEM, the distribution of the stress on the contact surfaces of the disc and the disc guide, was calculated. The influences of vibration on the distribution of the stress on the contact surfaces, together with the effect of the contact stress on the initiation of fretting fatigue cracks and fretting fatigue life have been studied. A critical plane approach the Smith Watson Topper fatigue parameter has also been adopted here, to predict crack initiation position and orientation, fatigue life. The results show that the predicted cracks location and fatigue life are well accordance with the practical situation.